WESTERN END OF NEWPORT NECK. 317 



Their usual color is greenish, and very frequently whitish; more sandy, thin 

 layers are interbedded, giving- the rock a banded appearance. This banded 

 character is well seen at various points on the east side of Brentons Point. 

 Sometimes the rock is rather quartzitic and is cleaved like the rock on the 

 hill east of Browns Point, east of Sakonnet River; one locality of this 

 kind is found along the east side of the road leading northward into the 

 Fort Adams grounds and southwest of Brentons Cove. Not infrequently 

 the shales are purplish in color, and where this is the case thin layers of 

 limestone are often intercalated in the shales. The same feature was noted 

 in the Little Compton shales, and suggests the identity of these shales. 

 Calcitic layers not being known from undoubted Carboniferous rocks, nor 

 having been found elsewhere in the field, suggests that the Brenton Point 

 shales are of pre-Carboniferous age. 



Layers of calcite are especially numerous around the vicinity of Pirates 

 Cave and the shore just south of the irregular headland a quarter of a mile 

 southeast of Castle Hill. Along the summit of Castle Hill some masses of 

 limestone occur, but it is not certain whether the material is in situ. Around 

 Brentons Cove, however, these interbedded calcitic layers are thicker and 

 apparently more common. 



The average strike of the above-described shales is N.-S., and the dip 

 30° to 40° E. However, on the southern and western shores of Brentons 

 Point the strike is frequently N. 30° W., varying at times to N. 70° W., 

 and the clip occasionally becomes almost horizontal, and near the southwest 

 end of Brentons Point and north of Pirates Cave becomes locally even 

 westward. The most northern exposure of the green shales on the neck 

 is south of the wharves on the east side of Fort Adams. A sixth of a 

 mile south of the wharves, at a prominent angle of the shore, the green 

 shale contains thick limes-tone layers. 



The existence of these limestone beds in the green shale series is of 

 importance, since nothing similar occurs in the undoubted Carboniferous 

 rocks. A limestone bed is found northeast of the stables on the prominent 

 angle of the shore at the southwest side of Brentons Cove. It strikes about 

 N. 10° E. and dips steeply eastward. A quarter of a mile northward, near 

 Fort Adams, the limestone occurs again, as already mentioned. Here it is 

 much crumpled, but seems in general to strike N. 70° E., dip southward. 



